A window grill is shaped like a rhombus whose diagonals are 1.2 m and 0.8 m. Find the area of the grill.

Class 8MensurationMensuration

Step-by-Step Solution

Area = ½ ×

1.2 \times 0.8

= ½

\times 0.96 = 0.48 m^{2}

. Trap

0.96 m^{2}

: forgetting the ½. Trap

2 m^{2}

: adding the diagonals (1.2 + 0.8), which is a length. Trap

0.24 m^{2}

: halving a second time.

Answer: A)

0.48 m^{2}

A cylinder is a circle stacked vertically. Two measurements: radius

r

and height

h

.

**Curved surface area (CSA) = 2π

r h

** (imagine 'unrolling' the curved surface — it becomes a rectangle of width 2π

r

and height h).

**Total surface area (TSA) = 2π

r^{2} + 2

r h = 2

r (r + h)

** (curved surface + two circular ends).

**Volume = π

r^{2}

h

** (area of circular base × height).

Use π = 22/7 when

r

is a multiple of 7; otherwise π ≈ 3.14.

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